Search results for "General Computer Science"
showing 10 items of 895 documents
Do graphical overviews facilitate or hinder comprehension in hypertext?
2009
Educational hypertexts usually include graphical overviews, conveying the structure of the text schematically with the aim of fostering comprehension. Despite the claims about their relevance, there is currently no consensus on the impact that hypertext overviews have on the reader's comprehension. In the present paper we have explored how hypertext overviews might affect comprehension with regard to (a) the time at which students read the overview and (b) the hypertext difficulty. The results from two eye-tracking studies revealed that reading a graphical overview at the beginning of the hypertext is related to an improvement in the participant's comprehension of quite difficult hypertexts…
Groups are not always the same
1993
The idea of supporting group meetings at the same time and at the same place by computer raises the problem of how salient features of group behaviors are understood in meetings. In this paper we take a critical look at several beliefs about group behaviors in research dealing with electronic meeting systems (EMS). The paper argues based on an empirical study that the concept of a small, cohesive business team, so widely held, in all EMS research is not necessarily a valid starting point in thinking of meeting support. In particular, the paper critically evaluates a number of beliefs of user aspects, group features such as composition, structure and protocols, and task characteristics such …
Extraction of objects from structured backgrounds in the cat superior colliculus. Part II
1980
Specific changes occur in the cells of the uppers layers of the cat's superior colliculus when a two dimensional noise (background) is superimposed onto a deterministic signal (spot of light). Some of the measurements can be interpreted as meaning that some cells only react to certain relative movements of object (spot) and background (noise). The movement of the visual background is interpreted as environmental movement occurring due to the animal's own movement. The results of the measurements provide all the necessary presuppositions for a distinction between the animal's own velocity and that of the object (Part I). The experimental results can be interpreted with a model. The essential…
HD-RTI: an adaptive multi-light imaging approach for the quality assessment of manufactured surfaces
2021
International audience; Reflectance Transformation Imaging (RTI) is a technique for estimating surface local angular reflectance from a set of stereo-photometric images captured with variable lighting directions. The digitization of this information fully fits into the industry 4.0 approach and makes it possible to characterize the visual properties of a surface. The proposed method, namely HD-RTI, is based on the coupling of RTI and HDR imaging techniques. This coupling is carried out adaptively according to the response at each angle of illumination. The proposed method is applied to five industrial samples which have high local variations of reflectivity because of their heterogeneity of…
Human-Robot Cooperation for Surface Repair Combining Automatic and Manual Modes
2020
[EN] This article develops a human-robot cooperation to carry out treatments such as sanding, polishing, etc. on the surface of a known rigid object. For this purpose, a vision system is considered to get the object location to ensure not only the perpendicularity of the obot tool to the object surface but also a smooth approach of the tool to the surface. In order to add flexibility, the proposal includes the simultaneous combination of automatic and manual modes of operation. Thus, the human user can guide the robot tool to treat arbitrary areas (manual mode) and, when the operator releases the tool, the robot goes into the automatic mode to treat prior established areas. The method uses …
Perception and replication of planar sonic gestures
2012
As tables, boards, and walls become surfaces where interaction can be supported by auditory displays, it becomes important to know how accurately and effectively a spatial gesture can be rendered by means of an array of loudspeakers embedded in the surface. Two experiments were designed and performed to assess: (i) how sequences of sound pulses are perceived as gestures when the pulses are distributed in space and time along a line; (ii) how the timing of pulses affects the perceived and reproduced continuity of sequences; and (iii) how effectively a second parallel row of speakers can extend sonic gestures to a two-dimensional space. Results show that azimuthal trajectories can be effectiv…
Computer simulations to approach surface tension by means of a simple mesoscopic mechanical model
2019
A small insect can stand or walk on water surface, drops of mercury do not spread on a solid surface, and a meniscus is formed at the free surface of a liquid contained in a thin vessel. These phenomena can be seen as macroscopic manifestations of molecular interactions and can be explained macroscopically in terms of surface tension. In this study, we deal with an approach to surface tension from a mechanical point of view, presenting a simple mesoscopic mechanical model of surface tension and the results of its implementation in numerical fluid dynamics simulations. Particularly, phenomena like droplet formation without gravity and with gravity when it can drop from a narrow hole like a t…
Learning by doing. Case study: Education for sustainable development at the University of Latvia
2019
Junction of possibilities offered by European research programmes in the tertiary education and technology enhanced learning open up new borders for students and young researchers; especially for the ones from institutions with less strong collaboration links to Western-Europe and overseas. University of Latvia has undertaken the challenge of designing master’s programme on education for sustainable development called ‘Natural Sciences, Global Change and Technologies for Sustainable Development’ combined with application of digital learning tools. Teaching staff was formed form several faculties of the University of Latvia, other universities, respective companies as well as foreign partner…
Can international environmental cooperation be bought?
2010
In this paper a two-stage game of international environmental agreement formation with asymmetric countries is analytically solved. The equilibrium of the game makes it possible to determine the size and composition of a stable agreement. Two cases are studied. In the first case, countries differ only in abatement costs, while in the second case, they differ in environmental damages. In both cases, two different institutional settings, one without transfers and another with transfers, are considered. The results establish that the asymmetry assumption has no important effects on the scope of cooperation in comparison with the symmetric case if transfers are not used or abatement costs repre…
Electronic structure trends of Möbius graphene nanoribbons from minimal-cell simulations
2014
Investigating topological effects in materials requires often the modeling of material systems as a whole. Such modeling restricts system sizes, and makes it hard to extract systematic trends. Here, we investigate the effect of M\"obius topology in the electronic structures of armchair graphene nanoribbons. Using density-functional tight-binding method and minimum-cell simulations through revised periodic boundary conditions, we extract electronic trends merely by changing cells' symmetry operations and respective quantum number samplings. It turns out that for a minimum cell calculation, once geometric and magnetic contributions are ignored, the effect of the global topology is unexpectedl…